JPH0688724A - Scanning-type probe microscope, memory device and lithography apparatus - Google Patents

Abstract

PURPOSE:To prevent relative position deviation between a probe and a sample for a long period immediately after the setting of an apparatus by sequentially performing correcting action based on the pure position deviation amount, from which a scanning- signal component caused by the scanning of the probe is removed. CONSTITUTION:A mirror A 104 is attached to an xy driving element 103, which operates a probe 102 with respect to a sample 101. Light having two wavelengths, which are orthogonally polarized to each other, is split into two parts. One is reflected from the mirror 104 through a 1/4-wavelength phase plate A 112. The other is reflected from a mirror A' 114 through a 1/4-wavelength phase plate A' 113. Two reflected lights are synthesized with a polarization beam splitter A 111. The result is cast into a sensor 116 and becomes the light intensity signal. The phase difference between the oscillating components of the oscillating numbers in a reference-light intensity signal and a light intensity signal is detected with a synchronization detecting circuit. Thus, the relative moving amount of the mirror 104 and the mirror 114 can be detected in high resolution. The correcting action is sequentially performed based on the pure position deviation caused by the scanning of the probe 102. Therefore, readjustment is not required.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning probe microscope apparatus, a memory apparatus and a lithographic apparatus having a position deviation correcting function.

[0002]

2. Description of the Related Art In recent years, a scanning probe microscope (SPM), which far exceeds the resolution of conventional electron microscopes, has been put into practical use, and it has become possible to observe the surface of various samples with a resolution of 0.1 nanometer or less. . In SPM, a probe with a sharp tip is brought close to the sample surface to a distance of about 1 nanometer or less, and a physical quantity generated between them is detected. The probe is two-dimensionally scanned with respect to the sample surface. Then, the SPM image is obtained by two-dimensionally mapping the physical quantity at each point on the sample surface.

The above-mentioned physical quantities include tunnel current and atomic force, and thus SPM can be classified into various types such as scanning tunneling microscope (STM) and atomic force microscope (AFM).

When the surface of the sample is actually observed using SPM, the probe is laterally moved relative to the sample due to relaxation of mechanical strain and temperature drift that occur when the sample and the probe are replaced. The position is displaced, and the SPM observation image is displaced or distorted. The relaxation time for this misalignment is generally about 2 to 5 hours. SPM observation and SPM configuration
In a lithographic apparatus or a memory device to which the principle is applied, when trying to perform detailed observation or precise processing / recording / reproducing / erasing in a region on the order of 1 to 10 nm or less, a long time is waited after setting the device. However, there is a problem that work efficiency is reduced.

Therefore, in the STM, the follow-up speed is determined from the position displacement speed of the STM observation image, a signal whose size changes at a constant speed is applied to the lateral drive element of the probe, and the lateral change due to drift of the probe and the sample is applied. A proposal has been made to follow the positional deviation at a constant speed.
It is disclosed in Japanese Patent Publication No.

[0006]

However, in the above-mentioned conventional example, since the following speed is determined from the position deviation speed of the STM observation image, if the position deviation speed changes due to the relaxation of the position deviation, the following speed is readjusted accordingly. There is a problem that it is necessary and time-consuming.

Further, when the position displacement speed is large immediately after the device is set, there is a problem that the STM image is largely distorted due to the position displacement and it is difficult to adjust the following speed.

Further, when the observation is performed for a long time, or when the displacement speed is high even for a short time, the displacement amount may exceed the optimum control range of the tracking actuator. In that case, the STM observation is performed. Had to interrupt and drive the other coarse actuator.

The present invention has been made in view of the problems of the above-mentioned conventional techniques, and a relative displacement between the probe and the sample occurs for a long time immediately after the setting of the apparatus. The purpose is to realize a device without

[0010]

The scanning probe microscope of the present invention includes a probe arranged such that its tip is opposed to and close to the surface of the sample, and a probe for the sample. And a detection means for detecting a physical quantity generated between the sample and the probe, the scanning means being orthogonal to the facing direction and scanning relative to a predetermined path. In the scanning probe microscope that observes the sample surface from the detection result of the detection means, at the time of scanning the probe, detects the relative position of the sample and the probe in the direction orthogonal to the facing direction of the sample and the probe, A positional deviation amount detection unit that outputs a first positional deviation amount detection signal indicating the detection content, and a signal component associated with the scanning of the sample and the probe is removed from the first positional deviation amount detection signal. Output as the position deviation detection signal It has a scanning signal No. component removing means, and correction means for sequentially correcting a positional deviation between the sample and the probe on the basis of the second deviation amount detection signal.

In this case, the scanning signal component removing means may be a low pass filter having a cutoff frequency lower than the scanning frequency of the sample and the probe.

Further, the scanning signal component removing means may sample the positional deviation amount detection signal at a timing synchronized with the scanning of the sample and the probe.

In this case, the scanning signal component removing means may interpolate between the sampling points.

Further, the scanning performed by the scanning means may be performed by a folding signal which is smooth near the folding point, and the sampling operation by the scanning signal component removing means may be performed near the folding point.

Further, each of the positional deviation amount detecting means may be constituted by a light wave interferometer.

In this light wave interferometer, a mirror fixed to a member for fixing a sample, a mirror fixed to a member for fixing a probe, and means for injecting coherent light into one of the mirrors, Means for separating a part of the coherent light and changing the optical path to make it enter the other side of the mirror, and means for calculating the relative movement amount of the mirror based on the combined light intensity signal of the two reflected lights from the mirror. It may be a differential type light wave interferometer consisting of

The light wave interferometer includes a mirror fixed to either one of a member for fixing a sample and a member for fixing a probe, an optical fiber fixed to the other and arranged with its end face close to the mirror. Relative to the end face of the optical fiber based on the combined light intensity signal of the means for injecting the coherent light into the mirror through the optical fiber and the light reflected by the mirror and passing through the optical fiber again It may be an optical fiber interferometer including a means for calculating the target movement amount.

In each of the above-mentioned configurations, the correction unit estimates the temporal displacement of the displacement amount based on the second displacement amount detection signal output from the scanning signal component removal unit, and the estimation circuit. It is also possible to have a subtraction circuit that corrects the positional deviation between the sample and the probe based on the estimation result and the set position according to the predetermined course.

The estimating operation of the estimating circuit may be designed to estimate the intensity and time constant of these components by targeting at least one positional deviation amount due to relaxation times of different time constants.

Further, the estimation circuit inputs the second input signal when the difference between the input second positional deviation signal and the estimated value from the second positional deviation signal before the input exceeds a predetermined value. The estimated value from the second positional deviation amount signal before the input may be output without performing the estimation based on the positional deviation amount signal.

Each of the above-mentioned correction means includes a first actuator and a second actuator that moves including the first actuator.
The actuators may be used to correct the positional deviation between the sample and the probe by using each of these actuators.

Further, the memory device and the lithographic apparatus of the present invention use the above-mentioned configuration of the scanning probe microscope.

[0023]

Since the correction operation performed in the present invention is sequentially performed based on the pure positional deviation amount in which the scanning signal component accompanying the scanning of the probe is removed, the operation of the apparatus is continued for a long time immediately after the setting of the apparatus. In addition, it is possible to accurately correct the relative displacement between the probe and the sample caused by relaxation of mechanical strain, temperature drift, etc. without requiring readjustment.

The estimating means is provided in the correcting means for performing the above-mentioned correction, and the positional deviation is corrected based on the result of estimating the relative positional deviation between the probe and the sample caused by the relaxation of mechanical strain, temperature drift and the like. In this case, since the correction is made based on the relative positional deviation up to that time, malfunction due to mechanical and electrical noise that suddenly occurs can be prevented.

[0025]

Embodiments of the present invention will now be described with reference to the drawings.

1 and 2 are a sectional view and a top view showing the arrangement of the optical system of the positional deviation amount detecting means in one embodiment of the present invention.

Regarding the optical system of the present embodiment, first, the system in the z-axis direction will be described with reference to FIG.

The probe 102 is attached to the sample 101 by xy in the figure.
To the xy driving element 103 that relatively scans in the direction
Attach 104. On the other hand, the coherent light beams of two wavelengths λ ₁ and λ _{2 which} are polarized in directions orthogonal to each other are used as the polarization maintaining fiber 105.
It is introduced into the inside of the device casing 106 through the inside. The light emitted from the end face of the polarization maintaining fiber 105 is collimated by the collimator lens 107, and the beam splitter R
It is incident on 108. Part of the incident light is reflected, passes through the polarizing plate R109, and enters the sensor R101, and becomes a reference light intensity signal. The other is divided into four, and one of them is incident on the polarization beam splitter A111.

Here, the two-wavelength lights which are orthogonally polarized to each other are divided into two, one of which passes through the quarter-wave plate A 112 and is reflected by the mirror A 104, and the other passes through the quarter-wave plate A'113. It is reflected by the mirror A'114. Two
The two reflected lights are combined by the polarization beam splitter A111, pass through the polarizing plate A115, enter the sensor A116, and become the light intensity signal A.

Since both the reference light intensity signal and the light intensity signal A are combined light of two wavelengths (λ ₁ , λ ₂ ), the frequency Δf = C (1 / λ ₁ -1) is included in the light intensity signal. The vibration component of / λ ₂ ) is included. Here, C is the speed of light. By detecting the phase difference of the vibration component of the frequency Δf in the reference light intensity signal and the light intensity signal A by the synchronization detection circuit, the relative movement amount of the mirror A 104 and the mirror A ′ 114 in the x direction is detected. For example, if the wavelength of the two-wavelength coherent light is λ ₁ ≈λ ₂ = 67
When 0 nm and Δf = 1 MHz, the change 2π radian in the phase of the vibration component of the signal A with respect to the vibration component of the reference signal corresponds to the relative movement amount 335 (= 670/2) nm of the mirror A 104 and the mirror A ′ 114. . Further, by dividing the phase into 100 to 1000 and measuring the phase difference precisely, the relative movement amount can be detected with a resolution of 3 to 0.3 nm.

Next, with reference to FIG. 2, the optical system of the present embodiment on the xy plane will be described.

The collimated light emitted from the collimator lens 107 is incident on the beam splitter 201 except for a portion of the collimator lens 110 and is divided into two, and further divided into a total of four by the beam splitters 202 and 203. These lights are transmitted to the polarization beam splitter, the phase plate and the mirror B205, the mirror C204, the mirror D206, the mirror B'117, the mirror C '(not shown), and the mirror D' (not shown), which are provided for each of them, as described above. , Incident light or reflected light, and the combined light passes through a polarizing plate provided for each of the sensors B208, C
The light intensity signals B,
It becomes C and D. By detecting the phase difference between the vibration components of the light intensity signals B, C, D and the vibration component of the reference signal, the relative movement amount of the mirror B205 and the mirror B′117 in the x direction and the mirror C204 and the mirror are similar to the above. C ′ (not shown), and the relative movement amount of the mirror D 206 and the mirror D ′ (not shown) in the y direction are detected.

The mirror A 104 and the mirror A'114 and the mirror B 205 and the mirror B'117 are arranged at positions symmetrical with respect to the probe 102 and the sample 101 in the x direction.
The average of the x-direction relative movement amount of 104 and the mirror A ′ 114 and the x-direction relative movement amount of the mirror B 205 and the mirror B ′ 117 is defined as the x-direction relative movement amount of the probe 102 and the sample 101.
Similarly, the mirror C204 and the mirror C '(not shown) and the mirror D206 and the mirror D' (not shown) are also arranged at positions symmetrical with respect to the probe 102 and the sample 101 in the y direction, and the mirror C
An average of the y-direction relative movement amount of 204 and the mirror C ′ (not shown) and the y-direction relative movement amount of the mirror D206 and the mirror D ′ (not shown) is defined as the y-direction relative movement amount of the probe 102 and the sample 101. The optical system of the present embodiment is an optical system that does not affect the relative movement amount detection accuracy in the xy directions due to the relative movement of the probe 102 and the sample 101 in the z direction.

FIG. 3 is a diagram for explaining a device configuration for introducing into the polarization maintaining fiber two coherent light beams of two wavelengths which are polarized in directions orthogonal to each other.

In FIG. 3, the coherent light of wavelength λ ₁ emitted from the semiconductor laser 301 is collimated by the collimator lens 302, and the S-polarized light component in the direction perpendicular to the plane of the paper is collimated by the first polarization beam splitter 303. And P-polarized light components in different directions. The S-polarized component is the first mirror 3
After being reflected by 04, it is incident on the second polarization beam splitter 305. After the P-polarized component is reflected by the second mirror 306,
The acousto-optic modulator 307 modulates the frequency by Δf,
Shift the wavelength to λ ₂ . Here, between λ ₁ , λ ₂ and Δf, as described above, Δf = C (1 / λ ₁ −1 / λ ₂ )
Have a relationship. The P-polarized light component having the wavelength λ ₂ is further incident on the second polarization beam splitter 305, combined with the S-polarized light component, condensed by the condenser lens 308, and introduced into the polarization maintaining fiber 309.

Referring again to FIG. 1, a scanning probe microscope (SPM) to which the present invention is applied will be described.

In the scanning probe microscope, the tip of the probe 102 is moved to the surface of the sample 101 by the z-driving element 118 for 1 n.
Approach up to a distance of about m or less. Further, an xy driving circuit 1 which constitutes a scanning means with the xy two-dimensional scanning signal from the xy scanning signal circuit 119 together with the xy scanning signal circuit 119.
20, and an xy two-dimensional drive signal is input to the xy drive element 103 to cause the probe 102 to relatively scan the sample 101 in the xy two-dimensional manner. At this time, an SPM image is obtained by detecting a physical quantity between the tip of the probe 102 at each position on the surface of the sample 101 and mapping it in two dimensions. The physical quantity at this time is, for example, a tunnel current (scanning tunneling microscope: STM) flowing when a bias voltage is applied between the probe and the sample, an atomic force acting between the probe and the sample, Van der Waals. Force, frictional force, magnetic force (atomic force microscope: AFM, friction force microscope: FFM, magnetic force microscope: MFM), probe radiated from the back (optical fiber with sharp tip, glass surface with sharp tip) Evanescent light (photon scanning tunneling microscope: PST) that exudes from the sample surface with a thin metal coating and an opening with a diameter of 1 μm or less at the tip)
M, near-field optical microscope: NFOM), etc., and these microscopes are collectively called SPM.

In the SPM, as a method of two-dimensionally scanning the tip of the probe 102 with respect to the surface of the sample 101, raster scanning as shown in FIG. 4 is usually performed. This performs x scanning at a speed sufficiently higher than the scanning speed in the y direction, and x
This is a scanning method in which the scanning line in the direction is gradually shifted in the y direction to fill one screen. In the figure, the solid line indicates the forward scan in the y direction, and the broken line indicates the backward scan. Further, of the solid lines (broken lines), the one to which the rightward arrow is attached indicates the forward scanning in the x direction, and the one to which the leftward arrow is attached indicates the backward scanning in the x direction. Now, probe 1 for sample 101
If 02 does not cause any displacement other than scanning in the xy directions, the scanning regions due to reciprocal scanning in the y direction overlap as shown in FIG. 4, and the measurement region in SPM will not be displaced or distorted.

However, in the actual measurement, the probe is positioned in the xy direction relative to the sample during the SPM measurement due to the relaxation of the mechanical strain generated when the sample and the probe are exchanged and the temperature drift. The measurement area is displaced or distorted due to the displacement. Since this positional deviation occurs on the order of a longer time than the SPM measurement time (especially the time to obtain one screen), a phenomenon that occurs during SPM measurement is that a certain speed in the x direction as shown in FIG. Distortion of the measurement region caused by displacement occurs, enlargement or reduction of the measurement region caused by displacement at a certain speed in the y direction as shown in FIG. 6, or the case of FIGS. 5 and 6. Appears in the form of distortion and enlargement / reduction of the measurement region caused by positional displacement at a certain speed in a certain direction in the xy plane as if there were mixed.

A method of correcting the positional deviation of the probe relative to the sample in the xy directions to prevent such distortion and enlargement / reduction of the measurement region will be described below.

FIG. 7 is a diagram showing a signal processing circuit 721 for correcting the displacement in the x direction, and FIG. 8 is an example of signals obtained at some points in FIG. 7, and the operation of the signal processing circuit shown in FIG. FIG.

The output current signals of the vibration component of the frequency Δf from the sensor A (116 in FIG. 1), the sensor R (110 in FIG. 1) and the sensor B (208 in FIG. 1) are converted into current / voltage conversion circuits 701 to 703. Each is converted into a voltage signal.

The outputs of the current / voltage conversion circuits 701 to 703 are input to the synchronization detection circuits 704 to 707. Current /
The output of the voltage conversion circuit 701 is the synchronization detection circuits 704, 70.
5, respectively. The output of the current / voltage conversion circuit 702 is input to the synchronization detection circuits 704 and 707, and
After passing through the phase shifter 708, the synchronization detection circuits 705, 7
It is input to 06. The output of the current / voltage conversion circuit 703 is input to the synchronization detection circuits 706 and 707, respectively.

As described above, a part of the signal from the sensor R is included in the mirror A 104, the mirror A'114 and the mirror B2.
No. 05 and the mirror B ′ 117 are detected in the x direction relative movement direction, the phase is shifted through the phase shifter 708 by ¼ cycle of the vibration of the frequency Δf, and the synchronization detection circuit 70
5, 706.

The outputs from the sync detection circuits 704 to 707 are input to the low pass filters 709 to 712, respectively. The counter 7 is configured as movement amount signals S71 and S74 indicating the movement amounts output by the low-pass filters 709 and 712.
13 and 716, respectively, and the low-pass filter 7
The movement amount signals S72, S73 output by 10, 711 are
By passing through the binarization circuits 714 and 715, the counter 71 outputs movement direction signals S75 and S76 indicating the movement direction.
3, 716, respectively.

In the counters 713 and 716, the movement amount signals S71 to S of the mirrors A and A'and the mirrors B and B ', respectively.
74 and the movement direction signals S75 and S76, x indicating the relative positional deviation amount between the mirrors A and A ′ and the mirrors B and B ′ in the x direction.
The direction relative position deviation amount signals S77 and S78 are calculated and output to the averaging circuit 717. The sign of the signal at this time is positive in the positive direction of x in FIG.

In the averaging circuit 717, the sample 101 and the probe 102 are obtained by averaging the relative x-direction relative displacement amounts of the mirrors A and A ′ and the mirrors B and B ′ indicated by the x-direction relative displacement amount signals S77 and S78. And a relative position deviation amount signal 8b in the x direction, which is a first position deviation amount detection signal of Here, in the x-direction relative position deviation amount signal 8b, the position deviation component and the x-direction scanning component caused by relaxation of mechanical strain and temperature drift are mixed.
Of the above-described configuration of the signal processing circuit 721, the current / voltage conversion circuits 701 to 703 constitute detection means, and in addition thereto, the signal processing system of the positional deviation amount detection means is constituted.

FIGS. 8A to 8C show an x scanning signal 8a, an x direction relative positional deviation amount signal 8b, and a low pass filter 718 output 8c, respectively.

By passing the x-direction relative position deviation amount signal 8b through the low-pass filter 718, the position deviation signal (second position deviation amount detection signal) excluding the x-direction scanning component is obtained as the low-pass filter 718 output 8c. The output 8c of the low-pass filter 718 is passed through an estimation circuit 722, which will be described later, and an error signal between the output and a preset position in the x direction is calculated by a subtraction circuit 719, amplified by an amplification circuit 720, and then amplified by an amplification position circuit 721. As the output of
It is input to the x-direction drive circuit 120, and thereafter, feedback control is performed so that the x-direction positional relationship between the sample 101 and the probe 102 becomes the set position.

A typical frequency band of a signal in the signal processing circuit 721 for correcting the displacement in the x direction shown in FIGS. 7 and 8 will be illustrated. Output signals of the sensors A, R, B and input signals of the synchronization detection circuits 704 to 707 to 1 MHz (= Δ
f), the output signals of the low-pass filters 709 to 712 and the output signals 8b to 10 kHz of the averaging circuit 717, the x-direction scanning signal 8a to 100 Hz, the output signal of the low-pass filter 718, and the output signal of the amplifier circuit 720 to 1 Hz.

FIG. 9 is a diagram showing a signal processing circuit for y-direction positional deviation correction, and FIG. 10 is a diagram showing examples of signals obtained at some points in FIG.

A current / voltage conversion circuit 901 for inputting the output current signal of the vibration component of the frequency Δf from the sensor C (207 in FIG. 2), the sensor R (110 in FIG. 2), and the sensor D (209 in FIG. 2). ~ 903, synchronization detection circuits 904 to 907 for performing the subsequent processing, phase shifter 908, low pass filters 909 to 912, movement amount signals S91 to S94 output by each low pass filter, counters 913, 916, and relative positions output by each counter. Deviation amount signals S96, S97, binarization circuits 914, 91
5. Moving direction signals S95 and S9 output from each binarization circuit
Up to 6 is the same as the signal processing circuit for correcting the displacement in the x direction.

The y-direction relative positional deviation amounts of the mirror C204 and the mirror C '(not shown) and the mirror D206 and the mirror D' (not shown) are averaged by the averaging circuit 917 to obtain the y of the sample 101 and the probe 102. The direction relative positional deviation amount signal 10b is used.

10A to 10E, the y-direction scanning signal 10a and the y-direction relative position shift amount signal 10b, y are shown in FIGS.
A directional scanning synchronization signal 10c, a y-direction positional deviation amount sampling signal 10d, and an interpolation signal 10e are shown.

As shown in the figure, the y-direction relative position shift amount signal 10b contains a y-direction position shift component and a y-direction scanning component. The y-direction scanning frequency is lower than the x-direction scanning frequency, and the y-direction scanning frequency overlaps the frequency band of the positional deviation component caused by relaxation of mechanical strain and temperature drift. Therefore, unlike the case of the positional deviation in the x direction described above, it is difficult to separate the positional deviation component and the y direction scanning component by the low-pass filter. Therefore, the y-direction scanning synchronization signal 10c is generated in synchronization with the y-direction scanning signal 10a, and in synchronization with this, the sampling circuit 918 samples the y-direction relative displacement amount signal 10b. This y-direction positional deviation amount sampling signal 10d is input to the interpolation circuit 919, and the interpolation between the sampling points is made to be the interpolation signal 10e. As an interpolation method, it is desirable to use an interpolation with a curve of quadratic or higher so that the interpolation signal is smooth and does not cause bending. An interpolating signal 10e is used to estimate a prediction circuit 920 which will be described later.
The subtraction circuit 921 calculates an error signal between the output and a preset y-direction position, and the amplification circuit 922
After being amplified by, it is input to the y-direction drive circuit 120 as the output of the y-position correction signal circuit 923, and thereafter, the sample 101 and the probe 1
Feedback control is performed so that the y-direction positional relationship with 02 is at the set position.

A typical frequency band of a signal in the y-direction positional deviation correction signal processing circuit of FIGS. 9 and 10 will be illustrated.
Output signals of the sensors C, R, D and the synchronization detection circuit 904
˜907 input signal ˜1 MHz (= Δf), low pass filters 909 ˜912 output signal and averaging circuit 917
Output signal of ~ 100Hz, y direction scanning signal ~ 10Hz,
Output signals from the interpolation circuit 919 and the estimation circuit 920 are up to 1 Hz.

Next, the estimation circuit 7 will be described with reference to FIGS.
The signal processing at 22, 920 will be described.

Although the positional deviation is caused by a plurality of factors,
As time passes, the positional shift due to the relatively short relaxation time decreases, and the positional shift due to the long relaxation time becomes the main factor. This state is shown in FIG. The misregistration signals in the x and y directions input to the estimation circuit include misregistration components having a relatively short relaxation time as indicated by 1 to n in the figure and positions having a long relaxation time as indicated by a dotted line after n + 3. From the deviation component, or as shown in FIG. 12, a plurality of them are further combined.
If such a position shift signal ΔS is expressed as a time t, ΔS = {A ₁ exp (−B ₁ t) + A ₂ exp (−B ₂ t) + ... + Ct + D}
・ ΔX + {E ₁ exp (−F ₁ t) ＋ E ₂ exp (−F ₂ t) ＋ ・ ・ ・ ＋ Gt +
H} · ΔY However, A ₁ , A ₂ , ..., B ₁ , B ₂ , ..., C, D, E ₁ , E ₂ , ...,
_{F 1, F 2, ...,} G, H is a _{constant, B 1, B 2, ...} , F 1, F 2, ... are positive, X, Y are each x, represents the unit vector of the position in the y-direction.

The position shift signals ΔS in the x and y directions input to the estimation circuits 722 and 920 are calculated at a plurality of times t = t ₁ , t ₂ , t.
_3, ..., sampled at t _n, the constant A ₁ in formula above this value, A _2, ..., G, and calculates the H. Using this constant value, the positional deviation signal Δ at t = t _{n + 1} , t _{n + 2} , ...
One can infer S. Thus, multiple times t = t
Based on the position shift signals at ₁ , t ₂ , ..., t _n , the subsequent t
The position shift signal at = t _{n + 1} , t _{n + 2} , ... is estimated, and the position shift correction feedback control is performed based on this value. Therefore, even if sudden mechanical or electrical noise is mixed in the misalignment signal, it can be determined that noise is mixed by comparing the signal immediately before mixing and the signal after mixing,
It is possible to prevent the malfunction of the feedback control by removing the mixed signal and using the estimated value as the position deviation correction signal instead. In addition, since the amount of positional deviation can be predicted over time, the amount of positional deviation over time elapses, so that the optimum control range of the actuator for correcting positional deviation (xy drive element 103 in FIG. 1 in this embodiment). If it exceeds xy, another xy coarse actuator (not shown in FIG. 1) is used to move the sample 101 and the probe 102 to xy.
It is possible to perform the control at the optimum control position for the actuator for correcting the positional deviation when the time is relatively rough and the time is elapsed.

The correction operation by the above-described signal processing carried out in the present embodiment is of course improved in accuracy as the number of samplings increases, but as shown in FIGS. 11 and 12, immediately after the start of movement. In this case, since the positional shift due to a factor of a relatively short relaxation time different from the subsequent main factor of the positional shift becomes the main factor, there is no particular problem. Further, as the number of samplings increases, the calculation time required for making the estimation also becomes longer, so that it becomes impossible to follow the correction operation depending on the sampling interval. However, since the number of samplings in such a state is sufficient to achieve the required accuracy, it suffices to lengthen the sampling interval. For example, the sampling interval is gradually lengthened as the number of samplings increases. It may be configured to.

In this embodiment, as an interference optical system for detecting the relative movement amount of the sample and the probe, the differential type (= the movement amount of the mirrors A and A'as shown in FIGS. 1 and 2) is used. However, the present invention is not limited to this, other interference optical systems,
For example, as shown in the sectional view of FIG. 13 and the top view of FIG.
A heterodyne lightwave interferometer using a fiber may be used.

13 and 14, fiber fixtures A to D (1307, 1322, 1401, 1402)
Is fixed to the lower unit of the device housing 1308, and mirrors A to D (1305, 1306, 1405, 140).
6) relative movement amount with respect to the polarization-preserving fibers A to D (1
309, 1321, 1403, 1404) and is reflected from the mirrors A to D and then detected again from the optical path length of the coherent light returning to the fibers A to D again. The linearly polarized light dual-wavelength coherent light source 1310 that constitutes the above-mentioned detection system has the same configuration as that shown in FIG.
311, polarizing plates 1312, 1319, sensor R131
3, polarization beam splitter 1314, quarter wave plate 13
The separating operation and the detecting operation by 15, 1317, the lens 1316, the mirror 1318 and the sensor A 1320 are the same as those in the embodiment shown in FIGS.

The optical systems shown in FIGS. 13 and 14 are also xy by the relative movement of the probe 1302 and the sample 1301 in the z direction.
The optical system does not affect the accuracy of relative movement amount detection in the direction.

In the present embodiment, the xy-direction positional deviation correction is SP
Although the example applied to M is shown, the concept of the present invention is not limited to this, and the positional deviation correction accuracy (~ 1 nm) similar to that of SPM is required, and the periodic relative xy between the probe and the sample is required.
The present invention can be applied to a device for performing directional scanning, for example, a memory device in which a sample is replaced with a memory medium or a lithographic device in which a sample is replaced with a lithographic medium, using the configuration and principle of SPM.

However, in these devices, periodic xy scanning may be different from raster scanning. For example, in a memory device, a recording medium 1504 as shown in FIG.
When the recording data rows 1506 arranged in rows along the upper track 1505 are scanned at a constant speed in the y direction while periodically scanning in the x direction, the recording data rows 1506 are also concentric as shown in FIG. Trucks 1 lined up (or spiral)
There is a case in which the print data string 1602 is circularly scanned along the line 601, that is, xy-direction scanning is performed by a sine wave signal whose phase is shifted by 1/4 cycle.

In the case of scanning the print data string shown in FIG. 15A, the true position shift signal 1503 is added to the x-direction scanning signal 1502 as shown in FIG. The displacement signal 1501 is generated, and the locus of the probe scanning is as shown by the broken line in FIG. The relative positional deviation amount in the x direction is subjected to the same signal processing as in FIGS. 7 and 9, and the true positional deviation signal 1503 is obtained by removing the x-direction scanning signal 1502 component from the apparent positional deviation signal 1501. The component is obtained, and the relative positional deviation between the recording medium 1504 and the probe (not shown in FIG. 15) is corrected.

In the case of scanning the print data string shown in FIG. 16A, the y-direction scanning signal 1606 and the x-direction scanning signal 1609 are true as shown in FIGS. 16B and 16C. Position shift signals 1605 and 1608 are added to generate apparent position shift signals 1605 and 1608, and the locus of the probe scanning is as shown by the broken line in FIG. 16A. Also for these, similar signal processing is performed for the relative positional deviation amount in both x and y directions, and x and y
It is possible to correct the relative positional deviation in both directions.

Although the above-described x-direction positional deviation correction signal processing circuit has the configuration shown in FIGS. 7 and 8, it may be the one shown in FIGS. 9 and 10. At this time, the frequency of the scanning signal in the x direction is higher than that of the scanning signal in the y direction. Is likely to occur. Therefore, as shown in FIG. 17A, the x-direction scanning signal 17a
Is preferably a waveform composed of a smooth curve such as a sine wave signal without a sudden inversion.

When the x-direction scanning signal 17a as shown in Z417 (a), the x-direction relative position shift amount signals 17b, x
FIG. 17 shows the directional scanning synchronization signal 17c, the x-direction positional deviation amount sampling signal 17d, and the interpolation signal 17e.
It shows in (b)-(e).

The sampling position is shown in FIG.
As shown in (d), the error does not occur in the vicinity of the point where the relative position deviation speed of the scanning turn-back portion becomes zero.

[0071]

Since the present invention is constructed as described above, it has the following effects.

According to any one of claims 1 to 8, the scanning probe microscope does not cause relative displacement between the probe and the sample during operation of the apparatus for a long time immediately after setting the apparatus. There is an effect that can be.

According to the ninth to eleventh aspects, in addition to the above effects, there is an effect that it is possible to prevent malfunction of the positional deviation correction control due to mechanical and electrical noise.

According to the twelfth aspect, in addition to the above respective effects, there is an effect that the control can be performed at the optimum control position of the actuator for correcting the positional deviation.

According to the thirteenth and fourteenth aspects, there is an effect that a memory device and a lithographic apparatus that achieve the above respective effects can be realized.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of the present invention.

FIG. 2 is a top view of the embodiment shown in FIG.

FIG. 3 is a diagram showing a configuration of an apparatus that introduces dual-wavelength coherent light polarized in mutually orthogonal directions into a polarization-maintaining fiber.

FIG. 4 is a diagram for explaining raster scanning of a probe in a scanning probe microscope.

FIG. 5 is a diagram for explaining a case where a displacement in the x direction occurs during raster scanning.

FIG. 6 is a diagram for explaining a case where a y-direction positional deviation occurs during raster scanning.

FIG. 7 is a diagram for explaining an x-direction position correction signal circuit.

FIG. 8 is a signal waveform diagram in the x-direction position correction signal circuit.

FIG. 9 is a diagram for explaining a y-direction position correction signal circuit.

FIG. 10 is a signal waveform diagram in the y-direction position correction signal circuit.

FIG. 11 is a signal waveform diagram in the estimation circuit.

FIG. 12 is an estimation circuit signal waveform diagram in which a plurality of positional deviation components having different relaxation times are combined.

FIG. 13 is a vertical cross-sectional view of a scanning probe microscope apparatus of an example using a heterodyne interference optical system using fibers.

FIG. 14 is a cross-sectional view of a scanning probe microscope apparatus of an example using a heterodyne interference optical system using fibers.

FIG. 15 is an explanatory diagram of an example in which the present invention is applied to a memory device.

FIG. 16 is an explanatory diagram of an example in which the present invention is applied to a memory device.

FIG. 17 is a signal waveform diagram of another signal processing method in x-direction position correction.

[Explanation of symbols]

 101 sample 102 probe 103 xy drive element 104 mirror A 105 polarization maintaining fiber 106 device housing 107 collimator lens 108 beam splitter R 109 polarizing plate R 110 sensor R 111 polarizing beam splitter A 112 phase plate A 113 phase plate A ′ 114 mirror A ′ 115 polarizing plate A 116 sensor A 117 mirror B ′ 118 z driving element 119 xy scanning signal circuit 120 xy driving circuit 201, 202, 203 beam splitter 204 mirror C 205 mirror B 206 mirror D 207 sensor C 208 sensor B 209 sensor D 301 semiconductor laser 302 collimator lens 303 first polarization beam splitter 304 first mirror 305 second polarization beam splitter 306 second mirror 307 sound Resonance modulator 308 Condensing lens 309 Polarization preserving fiber 701, 702, 703 Current / voltage conversion circuit 704, 705, 706, 707 Synchronization detection circuit 708 Phase shifter 709, 710, 711, 712 Low pass filter 713 Counter 714, 715 Binarization circuit 716 Counter 717 Averaging circuit 718 Low-pass filter 719 Subtraction circuit 720 Amplification circuit 721 Signal processing circuit 722 Prediction circuit 901, 902, 903 Current / voltage conversion circuit 904, 905, 906, 907 Synchronization detection circuit 908 Phase shifter 909 , 910, 911, 912 Low-pass filter 913 Counter 914, 915, Binarization circuit 916 Counter 917 Averaging circuit 918 Sampling circuit 919 Interpolation circuit 920 Prediction circuit 921 Subtraction circuit 922 amplification circuit 923 signal processing circuit 1301 sample 1302 probe 1303 xy drive element 1304 z drive element 1305 mirror A 1306 mirror B 1307 fiber fixture A 1308 device housing 1309 polarization preserving fiber A 1310 orthogonal polarization dual wavelength coherent light source 1311 Beam splitter 1312 Polarizing plate 1313 Sensor R 1314 Polarizing beam splitter 1315 1/4 wavelength plate 1316 Lens 1317 1/4 wavelength plate 1318 Mirror 1319 Polarizing plate 1320 Sensor A 1321 Polarization preserving fiber B 1322 Fiber fixing tool B 1401 Fiber fixing tool C 1402 Fiber fixing device D 1403 Polarization maintaining fiber C 1404 Polarization maintaining fiber D 1405 Mirror C 1406 Mirror D 1501 Apparent position Displacement signal 1502 x-direction scanning signal 1503 True position displacement signal 1504 Recording medium 1505 Track 1506 Recording data sequence 1601 Track 1602 Recording data sequence 1604 Apparent displacement signal 1605 True displacement signal 1606 Y-direction scanning signal 1607 Apparent Displacement signal 1608 True displacement signal 1609 x-direction scanning signal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Tagawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (14)

[Claims] 1. A probe arranged such that its tip is opposed to and close to the surface of the sample, and the probe is perpendicular to the facing direction of the sample with respect to the sample, and is predetermined. The scanning means for relatively scanning the track and the detecting means for detecting a physical quantity generated between the sample and the probe, and the detection result of the detecting means at the time of scanning by the scanning means In a scanning probe microscope for observing a sample surface, when scanning the probe, the relative position between the sample and the probe in a direction orthogonal to the facing direction of the sample and the probe is detected, and the detected content is A positional deviation amount detecting means for outputting a first positional deviation amount detection signal, and a signal component associated with scanning of the sample and the probe from the first positional deviation amount detection signal, Output as misregistration amount detection signal That the scanning signal component removing means, said second deviation amount detection signal on the basis of sequentially correcting the positional displacement between the probe and the sample correction means and a scanning probe microscope characterized by having a. 2. The scanning probe microscope according to claim 1, wherein the scanning signal component removing means is a low-pass filter having a cutoff frequency lower than the scanning frequency of the sample and the probe. Probe microscope. 3. The scanning probe microscope according to claim 1, wherein the scanning signal component removing means samples the positional deviation amount detection signal at a timing synchronized with the scanning of the sample and the probe. Type probe microscope. 4. The scanning probe microscope according to claim 3, wherein the scanning signal component removing means interpolates between sampling points. 5. The scanning probe microscope according to claim 3 or 4, wherein the scanning performed by the scanning means is performed by a folding signal which is smooth in the vicinity of the folding point, and is scanned by the scanning signal component removing means. A scanning probe microscope, wherein the sampling operation is performed in the vicinity of the turning point. 6. The scanning probe microscope according to any one of claims 1 to 5, wherein the positional deviation amount detecting means is a light wave interferometer. 7. The scanning probe microscope according to claim 6, wherein the light wave interferometer is one of a mirror fixed to a member fixing a sample, a mirror fixed to a member fixing a probe, and a mirror. Based on the means for injecting the coherent light into one side, the means for separating a part of the coherent light and changing the optical path to enter the other side of the mirror, and the combined light intensity signal of the two reflected lights from the mirror. A scanning probe microscope, wherein the scanning probe microscope is a differential type light wave interferometer including a means for calculating a relative movement amount of a mirror. 8. The scanning probe microscope according to claim 6, wherein the light wave interferometer has a mirror fixed to one of a member for fixing the sample and a member for fixing the probe, and an end surface fixed to the other. , A composite light intensity signal of the optical fiber arranged close to the mirror, the means for injecting the coherent light into the mirror through the optical fiber, the light reflected by the mirror and passing through the optical fiber again, and the light in which a part of the coherent light is separated in advance. A scanning probe microscope, which is an optical fiber interferometer comprising means for calculating a relative movement amount of a mirror with respect to an end face of an optical fiber based on the above. 9. The scanning probe microscope according to any one of claims 1 to 8, wherein the correction unit is based on the second positional deviation amount detection signal output from the scanning signal component removal unit, and the positional deviation amount is based on the positional deviation amount. And a subtraction circuit that corrects the positional deviation between the sample and the probe based on the estimation result of the estimation circuit and the set position according to the predetermined course. Characteristic scanning probe microscope. 10. The scanning probe microscope according to claim 9, wherein the estimating operation in the estimating circuit targets at least one or more positional deviation amounts due to relaxation times of different time constants, and the intensity and time constant of these components. The scanning probe microscope is characterized by: 11. The scanning probe microscope according to claim 9 or 10, wherein the estimating circuit estimates the value from the input second positional deviation amount signal and the second positional deviation amount signal before the input. And a means for outputting an estimated value from the second positional deviation amount signal before the input, without performing the estimation by the input second positional deviation amount signal when the difference between the input signal and the second positional deviation signal exceeds a predetermined value. Characteristic scanning probe microscope. 12. The scanning probe microscope according to claim 1, wherein the correction means includes a first actuator and a second actuator that moves including the first actuator. , A scanning probe microscope characterized by correcting the positional deviation between the sample and the probe by using each of these actuators. 13. A memory device for performing recording or reading on a recording medium by using the configuration of the scanning probe microscope according to claim 1. Description: 14. A lithographic apparatus, wherein recording is performed on a recording medium by using the configuration of the scanning probe microscope according to claim 1. Description: